All the possible interface specific options are detailed below. Each
option has to be terminated by a semicolon.

Prefix definitions are of the form:

prefix prefix/length {
list of prefix specific options
};

Prefix can be network prefix or the address of the inferface.
The address of interface should be used when using Mobile IPv6
extensions.

Special prefix "::/64" is also supported on systems that implement getifaddrs()
(on other systems, configuration activation fails and radvd exits).
When configured, radvd
picks one non-link-local prefix assigned to the interface and starts advertising
it. This may be applicable in non-6to4 scenarios where the upstream prefix might
change. This option is incompatible with Base6to4Interface option.
AdvRouterAddr option is always enabled when this configuration is used.

All the possible prefix specific options are described below. Each
option has to be terminated by a semicolon.

Decimal values are allowed only for MinDelayBetweenRAs,
MaxRtrAdvInterval and MinRtrAdvInterval. Decimal values should
be used only when using Mobile IPv6 extensions.

Route definitions are of the form:

route prefix/length {
list of route specific options
};

The prefix of a route definition should be network prefix; it can be used to
advertise more specific routes to the hosts.

RDNSS (Recursive DNS server) definitions are of the form:

RDNSS ip [ip] [ip] {
list of rdnss specific options
};

By default radvd will send route advertisements so that every node on the link can use them.
The list of clients (IPv6 address) to advertise to, and accept route solicitations from can be configured.
If done, radvd does not send send messages to the multicast addresses but
to the configured unicast addresses only. Solicitations from other addresses are refused.
This is similar to UnicastOnly but includes periodic messages and incoming client access
configuration. See examples section for a use case of this.

The definitions are of the form:

clients {
list of IPv6 addresses
};

INTERFACE SPECIFIC OPTIONS

IgnoreIfMissingon|off

A flag indicating whether or not the interface is ignored
if it does not exist at start-up. By default, radvd exits.

This is useful for dynamic interfaces which are not active when radvd
starts or which are dynamically disabled and re-enabled during the time
radvd runs.

A flag indicating whether or not the router sends
periodic router advertisements and responds to
router solicitations.

This option no longer has to be specified first, but it
needs to be
on
to enable advertisement on this interface.

Default: off

UnicastOnlyon|off

Indicates that the interface link type only supports unicast.
This will prevent unsolicited advertisements from being sent, and
will cause solicited advertisements to be unicast to the
soliciting node. This option is necessary for non-broadcast,
multiple-access links, such as ISATAP.

Default: off

MaxRtrAdvInterval seconds

The maximum time allowed between sending unsolicited multicast
router advertisements from the interface, in seconds.

Must be no less than 4 seconds and no greater than 1800 seconds.

Minimum when using Mobile IPv6 extensions: 0.07.

For values less than 0.2 seconds, 0.02 seconds is added to account for
scheduling granularities as specified in RFC3775.

Default: 600 seconds

MinRtrAdvInterval seconds

The minimum time allowed between sending unsolicited multicast
router advertisements from the interface, in seconds.

Must be no less than 3 seconds and no greater than 0.75 *
MaxRtrAdvInterval.

Minimum when using Mobile IPv6 extensions: 0.03.

Default: 0.33 * MaxRtrAdvInterval

MinDelayBetweenRAs seconds

The minimum time allowed between sending multicast
router advertisements from the interface, in seconds.

This applies to solicited multicast RAs.
This is defined as the protocol constant MIN_DELAY_BETWEEN_RAS in RFC4861.
MIPv6 redefines this parameter to have a minimum of 0.03 seconds.

Minimum when using Mobile IPv6 extensions: 0.03.

Default: 3

AdvManagedFlagon|off

When set, hosts use the administered (stateful) protocol for address
autoconfiguration in addition to any addresses autoconfigured using
stateless address autoconfiguration. The use of this flag is
described in RFC 4862.

Default: off

AdvOtherConfigFlagon|off

When set, hosts use the administered (stateful) protocol for
autoconfiguration of other (non-address) information. The use of
this flag is described in RFC 4862.

Default: off

AdvLinkMTU integer

The MTU option is used in router advertisement messages to insure
that all nodes on a link use the same MTU value in those cases where
the link MTU is not well known.

If specified, i.e. not 0, must not be smaller than 1280 and not greater
than the maximum MTU allowed for this link (e.g. ethernet has
a maximum MTU of 1500. See RFC 4864).

Default: 0

AdvReachableTime milliseconds

The time, in milliseconds, that a node assumes a neighbor is
reachable after having received a reachability confirmation. Used
by the Neighbor Unreachability Detection algorithm (see Section
7.3 of RFC 4861). A value of zero means unspecified (by this router).

Must be no greater than 3,600,000 milliseconds (1 hour).

Default: 0

AdvRetransTimer milliseconds

The time, in milliseconds, between retransmitted Neighbor
Solicitation messages. Used by address resolution and the Neighbor
Unreachability Detection algorithm (see Sections 7.2 and 7.3 of RFC 4861).
A value of zero means unspecified (by this router).

Default: 0

AdvCurHopLimit integer

The default value that should be placed in the Hop Count field of
the IP header for outgoing (unicast) IP packets. The value should
be set to the current diameter of the Internet. The value zero
means unspecified (by this router).

Default: 64

AdvDefaultLifetime seconds

The lifetime associated with the default router in units of seconds.
The maximum value corresponds to 18.2 hours. A lifetime of 0
indicates that the router is not a default router and should not
appear on the default router list. The router lifetime applies only
to the router's usefulness as a default router; it does not apply to
information contained in other message fields or options. Options
that need time limits for their information include their own
lifetime fields.

Must be either zero or between MaxRtrAdvInterval and 9000 seconds.

Default: 3 * MaxRtrAdvInterval (Minimum 1 second).

AdvDefaultPreferencelow|medium|high

The preference associated with the default router, as either "low",
"medium", or "high".

Default: medium

AdvSourceLLAddresson|off

When set, the link-layer address of the outgoing interface is
included in the RA.

Default: on

AdvHomeAgentFlagon|off

When set, indicates that sending router is able to serve as Mobile
IPv6 Home Agent. When set, minimum limits specified by Mobile IPv6
are used for MinRtrAdvInterval and MaxRtrAdvInterval.

Default: off

AdvHomeAgentInfoon|off

When set, Home Agent Information Option (specified by Mobile IPv6)
is included in Router Advertisements. AdvHomeAgentFlag must also
be set when using this option.

Default: off

HomeAgentLifetime seconds

The length of time in seconds (relative to the time the packet is
sent) that the router is offering Mobile IPv6 Home Agent services.
A value 0 must not be used. The maximum lifetime is 65520 seconds
(18.2 hours). This option is ignored, if AdvHomeAgentInfo is not
set.

If both HomeAgentLifetime and HomeAgentPreference are set to their
default values, Home Agent Information Option will not be sent.

Default: AdvDefaultLifetime

HomeAgentPreference integer

The preference for the Home Agent sending this Router Advertisement.
Values greater than 0 indicate more preferable Home Agent, values
less than 0 indicate less preferable Home Agent. This option is
ignored, if AdvHomeAgentInfo is not set.

If both HomeAgentLifetime and HomeAgentPreference are set to their
default values, Home Agent Information Option will not be sent.

Default: 0

AdvMobRtrSupportFlagon|off

When set, the Home Agent signals it supports Mobile Router
registrations (specified by NEMO Basic). AdvHomeAgentInfo must also
be set when using this option.

Default: off

AdvIntervalOpton|off

When set, Advertisement Interval Option (specified by Mobile IPv6)
is included in Router Advertisements. When set, minimum limits
specified by Mobile IPv6 are used for MinRtrAdvInterval and
MaxRtrAdvInterval.

The advertisement interval is based on the configured MaxRtrAdvInterval
parameter except where this is less than 200ms. In this case,
the advertised interval is ( MaxRtrAdvInterval + 20ms ).

Default: off

PREFIX SPECIFIC OPTIONS

AdvOnLinkon|off

When set, indicates that this prefix can be used for on-link
determination. When not set the advertisement makes no statement
about on-link or off-link properties of the prefix. For instance,
the prefix might be used for address configuration with some of the
addresses belonging to the prefix being on-link and others being
off-link.

Default: on

AdvAutonomouson|off

When set, indicates that this prefix can be used for autonomous
address configuration as specified in RFC 4862.

Default: on

AdvRouterAddron|off

When set, indicates that the address of interface is sent instead of
network prefix, as is required by Mobile IPv6. When set, minimum
limits specified by Mobile IPv6 are used for MinRtrAdvInterval and
MaxRtrAdvInterval.

Default: off

AdvValidLifetime seconds|infinity

The length of time in seconds (relative to the time the packet is
sent) that the prefix is valid for the purpose of on-link
determination. The symbolic value
infinity
represents infinity (i.e. a value of all one bits (0xffffffff)).
The valid lifetime is also used by RFC 4862.

Note that clients will ignore AdvValidLifetime of an existing prefix
if the lifetime is below two hours, as required in RFC 4862 Section 5.5.3
point e).

The length of time in seconds (relative to the time the packet is
sent) that addresses generated from the prefix via stateless address
autoconfiguration remain preferred.
The symbolic value
infinity
represents infinity (i.e. a value of all one bits (0xffffffff)).
See RFC 4862.

If this option is specified, this prefix will be combined with the
IPv4 address of interface
name
to produce a valid 6to4 prefix. The first 16 bits of this prefix
will be replaced by
2002
and the next 32 bits of this prefix will be replaced by the IPv4
address assigned to interface
name
at configuration time. The remaining 80 bits of the prefix (including
the SLA ID) will be advertised as specified in the configuration file.
See the next section for an example.

If interface
name
is not available at configuration time, a warning will be written to
the log and this prefix will be disabled until radvd is reconfigured.

This option enables systems with dynamic IPv4 addresses to update their
advertised 6to4 prefixes simply by restarting radvd or sending a SIGHUP
signal to cause radvd to reconfigure itself.

Note that 6to4 prefixes derived from dynamically-assigned IPv4 addresses
should be advertised with a significantly shorter lifetime (see the
AdvValidLifetime
and
AdvPreferredLifetime
options).

For more information on 6to4, see RFC 3056.

Default: 6to4 is not used

ROUTE SPECIFIC OPTIONS

AdvRouteLifetime seconds|infinity

The lifetime associated with the route in units of seconds.
The symbolic value
infinity
represents infinity (i.e. a value of all one bits (0xffffffff)).

Default: 3 * MaxRtrAdvInterval

AdvRoutePreferencelow|medium|high

The preference associated with the default router, as either "low",
"medium", or "high".

Default: medium

RDNSS SPECIFIC OPTIONS

AdvRDNSSPreference integer;

The preference of the DNS server, compared to other DNS servers advertised and used.
0 to 7 means less important than manually configured nameservers in resolv.conf, while 12 to 15 means more important.

NOTE: This feature was removed from the final RFC but can still be used for experimental purposes.

Default: 8

AdvRDNSSOpen on|off;

"Service Open" flag. When set, indicates that RDNSS continues to be available to hosts even if they moved to a different subnet.

NOTE: This feature was removed from the final RFC but can still be used for experimental purposes.

Default: off

AdvRDNSSLifetime seconds|infinity;

The maximum duration how long the RDNSS entries are used for name resolution. A value of 0 means the nameserver should no longer be used.
The maximum duration how long the RDNSS entries are used for name resolution. A value of 0 means the nameserver should no longer be used.
The value, if not 0, must be at least MaxRtrAdvInterval. To ensure stale
RDNSS info gets removed in a timely fashion, this should not be greater than
2*MaxRtrAdvInterval.

Default: 2*MaxRtrAdvInterval

EXAMPLES

It says that router advertisement daemon should advertise
(AdvSendAdvert on;) the prefix 2001:db8:0:1:: which has a lenght of 64
on the interface eth0. Also the prefix should be marked as autonomous
(AdvAutonomous on;) and as on-link (AdvOnLink on;). All the other
options are left on their default values.

To support movement detection of Mobile IPv6 Mobile Nodes, the
address of interface should be used instead of network prefix:

For 6to4 support, include the
Base6to4Interface
option in each prefix section. When using a dynamic IPv4 address, set
small prefix lifetimes to prevent hosts from retaining unreachable
prefixes after a new IPv4 address has been assigned. When advertising to on
a dynamic interface (e.g., Bluetooth), skip the interface if it is not
active yet.

Since 6to4 is enabled, the prefix will be advertised as
2002:WWXX:YYZZ:5678::/64, where WW.XX.YY.ZZ is the IPv4 address of
ppp0 at configuration time. (IPv6 addresses are written in hexadecimal
whereas IPv4 addresses are written in decimal, so the IPv4 address
WW.XX.YY.ZZ in the 6to4 prefix will be represented in hex.)

In this specific case, the configuration scripts may send HUP signal to
radvd when taking bnep0 up or down to notify about the status; in the
current radvd releases, sending HUP is no longer mandatory when the link
comes back up.